<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    .container {
      display: flex;
      flex-direction: column;
      background-color: #aaa;;
    }
    .inner {
      height: 194px;
      /* flex: 1; */
      background: coral;
    }
    /* .inner-2 {
      background: red;
      width: 300px;
      height: 194px;
      margin: 0 auto;
    } */
  </style>
</head>
<body>
  <div class="container">
    <div class="inner"><div class="inner-2"></div></div>
    <div class="inner"><div class="inner-2"></div></div>
    <div class="inner"><div class="inner-2"></div></div>
    <div class="inner"><div class="inner-2"></div></div>
  </div>
</body>
</html>